1. Technical Field
The present application relates in general to power generation in aircraft. More specifically, the present application relates to selective power augmentation within the drive system.
2. Description of Related Art
Aircraft engines within a drive system generate sufficient power to permit flight. Some maneuvers, such as takeoffs, auto-rotation, and landing, can require a greater amount of power from the engines than typically required in regular flight. Aircraft engines are sized to be able to generate this needed power at selected times and typically in short bursts. Because these maneuvers usually consist of a relatively small portion of the operational time of the aircraft, engines are regularly oversized.
For example, rotorcraft engines generally operate at a medium speed so as to deliver a medium power, e.g. the so-called maximum continuous power for a helicopter. However, aircraft engines are sometimes called upon to deliver higher power for a short period, such as maximum takeoff power for a helicopter. The need to deliver increased power output at selected times results in aircraft engines typically being oversized relative to medium power operation. This results in less efficiency, more fuel consumption, and greater weight on the aircraft.
Various systems have been developed to generate or store additional power for engines. Automotive vehicles use regenerative braking and/or dynamic braking, for example. Such systems use large sized battery banks to store electrical energy. These systems are typically heavy which could greatly limit the flight capacities of a rotorcraft. Furthermore, such systems are often continuously engaged to permit charging of the batteries when the engine is providing power. A drive system needs to be developed that permits greater efficiency while still providing additional power to the aircraft as required to perform a full range of maneuvers.
Although great strides have been made in the power generation of rotorcraft, considerable shortcomings remain.